In the united states, bee keepers lose a certain number of colonies over the winter. This is normal, but bee keepers maintain that losses of about 15 percent or less are “acceptable.” I don’t know what the logical or empirical basis for that number is, however.
Yesterday, the results of a report that surveys bee keepers in the US came out, and the total loss rate over the 2012/2013 winter was 31.1%. That’s a lot more than last year’s loss rate, but within the range of variation of loss over the last few years, as shown on this graph provided by “bee informed”:
This is not exactly the same thing as Colony Collapse Disorder, but overwintering loss is a different measure than overall colony loss. (It’s all related of course.)
The reason why this is important is that many crops rely on these honey bees for pollination.
The report cited here is preliminary, and there will be a more detailed version available in the near future.